Slashdot videos: Now with more Slashdot!

View

Discuss

Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

Necroloth and other readers sent in the story of Witricity's latest demo at the TED Global conference in Oxford, UK. The company is developing a system that can deliver power to devices without the need for wires. The idea is not new — electrical pioneers Thomas Edison and Nicola Tesla assumed that power would be delivered wirelessly. The BBC quotes the inventor behind Witricity's tech as saying that Tesla and Edison "...couldn't imagine dragging this vast infrastructure of metallic wires across every continent." eWeek Europe notes some hurdles the technology must overcome: "The 2007 experiment it is based on had an efficiency of only around 45 percent, but [Witricity's CEO] promised power delivered wirelessly would start out 15 percent more expensive than wires, and improve on that." Intel has also demonstrated wireless charging.

My grandmother worked for Thomas Edison - so I the FUD on Edison I can speak to directly as she was my intellectual mentor growing up - and yes we spent hours and hours talking about that crazy Edison.

Some points you should know:
Most of the consumer devices you use today are direct descendants of Edison's inventions.
Edison was no Crook either - even if only paying my sweet grandmother ~17 cents a day around the 1920's.
He was indeed eccentric toward the later years of his life however, and experienced what many would consider a form dementia today.

His list of inventions towers over just about all other modern inventors - I suggest all of you look them up - there are many, many stories to tell. From movies to music, refrigeration to your TV, he's been involved in some way.
...and by the way - it was Marconi that invented most of what was later attributed to Tesla... and returned to Marconi only recently by world courts.

Okay... so what about a taser that works by firing the "head" of the taser but without the trailing wires.

Heck, if that sort of approach worked (a huge "if" personally), the next obvious steps would be to miniaturize the "heads", perhaps make them burn out after a single use (cheap materials, built in resistor that burns out as the current crosses it)...... then pack a few of them into a magazine and we've created a rather nice "Assault Weapon" when you're trying to keep casualties to a minimum and are only dealing with "soft" targets (Law Enforcement/Security/Hostage applications sound the most likely).

I predict these are "five to ten years away".;)

YMMV but I still think it sounds like a neat concept, even if the technology can't/won't support the idea. The single biggest hurdle to the idea is the current need for a stun gun to have those wireless leads leading back to the "body" of the gun. If you can find a away to remove those (even if it means you are now firing a small projectile that isn't expected to penetrate much if anything), it can open the advancement up quite a bit.

But even with Tesla aside, this isn't new... it's just not as vastly useful as people re-discovering it seem to think it is. It doesn't work over gigantic distances, only moderate ones, and there's no engineering you can do to get around that.

The misunderstanding a lot of people have is that they think Tesla was chasing *truly* wireless power - when in fact this was probably never his goal. Tesla was always chasing after something he called "longitudinal waves" in an attempt to perform worldwide "wireless" power transmission - he even called one of his companies World Wireless [pbs.org].

Tesla certainly wasn't foolish enough to believe this distance was possible with purely wireless transmission, but instead investigated single-wire transmission systems using the ground as the single wire. His initial success at single-wire transmission was at Colorado Springs in 1900 with three lightbulbs in a closed circuit loop with no power source and a transmission source a hundred feet away. In this experiment, as in his later vacuum tube powering experiment performed at considerably greater distances (eventually miles away), the objects in question were always had a metallic contact with the ground.

Take a look at figures 3, 6, and 7 on this page: http://amasci.com/tesla/tmistk.html [amasci.com]. This seems the most likely explanation for the experiments at Colorado Springs and Wardenclyffe. Wardenclyffe in particular is where we find Tesla sinking iron rods 300 feet into the ground, burning out local power station dynamos with his energy demands, and constructing a massive omnidirectional transmission tower.

The reasonable conclusion from all this is that Tesla was always pursuing single-wire transmission schemes in which literally the entire Earth itself was the single wire, and the transmission medium for the wireless component was the entire ionosphere. "World Wireless" seems to have been meant quite literally, which was in keeping with all we know about Tesla's personality. Unfortunately, as we all know, Tesla needed something like an order of magnitude more funding than JP Morgan was willing to provide - particularly after Marconi.

Beyond that, though, Morgan would have probably pulled the project even if Tesla had gotten it working: if single-wire worldwide transmission was in fact his intention, it would've been impossible to meter consumption on a per-user basis.